Sometimes when using new substrates or items, you may encounter less than pleasing results when sublimating. Like using a third party brand of poly shirts, trying out an item no one has pressed before, or just trying to calibrate your press to a specific item that doesn’t work quite well enough with listed instructions. When one of these moments come up, you can use a technique to calibrate instructions called black box test.
Simply open your printing program and create a new document. Make a simple black box that’s a couple of inches squared. Normally, I recommend it be 2″ X 2″, but less or more can be applied as needed, so long as you can tell the output color on the item. Print it out with sublimation inks.
When you have printed your box transfer, take the substrate out that you want to use for testing. It’s best to use one that has already been pressed with a mistake-you can repress the item quite a few times before it’s covered too much to tell color correctly. Press the black box onto the item using the normal time, temperature, and pressure you would commonly use.
After pressing, take a look at your black box:
- If the black has a greenish tint, it hasn’t sublimated long enough and needs more time;
- If the black has a brownish tint, it’s been sublimated for too long and has lost color (needs less time);
- If the edges look kind of splotchy or has a runny look, you need to apply more pressure;
- If the entire box has a cloudy look or hazy areas, apply less pressure.
After adjusting, reprint the black box and press once again, following the above adjustments as indicated. Repeat the process using the same substrate as much as you can until you get a perfectly black box. Once you get the perfect color, record the time, temperature, and pressure used and try another substrate using the new settings.